1. Field of the Invention
This invention relates to a liquid crystal display (LCD) panel structure and method for manufacturing the same, and more particularly to an LCD panel structure driven by dot inversion and method for manufacturing the same.
2. Description of the Prior Art
FIGS. 1A and FIG. 1B show a conventional LCD panel, which comprises a color filter (CF) substrate 160, a thin film transistor (TFT) substrate 170, and a liquid crystal layer 150 injected in between the CF substrate 160 and the TFT substrate 170. A plurality of thin film transistors (TFTs) 105, gate lines 110, data lines 120, and pixel electrodes 140 are formed on the TFT substrate 170. A black matrix 164 and a plurality of color filters 162 are formed on the CF substrate 160. Each of the TFTs 105 mainly comprises a gate electrode 112, a gate insulating layer (not shown), a semiconductor layer 114, a source electrode 116, a drain electrode 118. The gate electrode 112 is electrically connected with a corresponding gate line 110; the source electrode 116 is electrically connected with a corresponding data line 120; and the drain electrode 118 is electrically connected with a corresponding pixel electrode 140. The alignment of liquid crystal molecules on the pixel electrode 140 is controlled by a voltage of the pixel electrode 140 applied through the TFT 105. However, the pixel electrode 140 of the conventional LCD panel is not covered the entire area surrounded with the data lines 120 and the gate lines 110. As shown in FIG. 1A, the pixel electrode 140 and the gate line 110, and the pixel electrode 140 and the data line 120 are spaced with a gap. Namely, the gate line 110 and the data line 120 are not covered by the pixel electrode 140. Hence, the alignment of the liquid crystal molecules on the gap can not be controlled by the pixel electrode 140, and a problem of light leakage will be generated in the gap.
In order to avoid the problem of light leakage, the opaque black matrix is formed on partial area of the CF substrate 160 corresponding to the gap. FIG. 1B is a cross-section schematic diagram along the line 1B-1B′ in FIG. 1A. An insulating layer 172 is formed on the TFT substrate 170, the data lines 120 and the pixel electrodes 140 are formed on the insulating layer 172, and a passivation layer 104 is covered on the data lines 120 and the pixel electrodes 140 to protect them. The black matrix 164 and the color filters 162 are formed on the lower surface of the CF substrate 160, the position of the black matrix 164 is corresponding to the area of light leakage, and the position of the color filters 162 are corresponding to the area of the pixel electrodes 140.
The structure of LCD panel mentioned above overcomes the problem of light leakage by using light-shielding structure of the black matrix 164. However, the assembly precision for combining the CF substrate 160 and TFT substrate 170 of LCD panel is not good. Consequently, the dimension of the black matrix 164 must be very larger than the dimension of the gap between the pixel electrodes 140 and the gate lines 110 and between the pixel electrodes 140 and the data lines 120 for defeating the assembly imprecision resulted in the light leakage. Nevertheless, the larger black matrix 164 will reduce an aperture ratio of the LCD panel. Therefore, U.S. Pat. No. 6,476,882 discloses the light-shielding structure formed on the TFT substrate 170. FIG. 1C shows a TFT substrate structure of a LCD panel of U.S. Pat. No. 6,476,882. In the present invention, the definition for source/drain of TFT is according to the common definition, and is different from the definition in the specification of the patent mentioned above. In such structure of LCD panel, an opaque light-shielding layer 125 is formed on the TFT substrate. In order to provide a more clear description for shapes and relationships of elements, the portions of the light-shielding layer 125 covered by the pixel electrode 140, the data line 120 and the protruding structure 122 is drawn with dot-line. Because the photolithography process is more accurate than the assembly process for the LCD panel, the dimension of the light-shielding layer 125 is smaller than the black matrix 164 shown in FIG. 1B. Hence, the aperture ratio can be increased by replacing the black matrix with the light-shielding layer mentioned above. Furthermore, the light-shielding layer has a repairing function of connecting the light-shielding layer with the protruding structure while the data line is broken.
Unfortunately, in the LCD panel mentioned above, gaps between the pixel electrode and the gate lines, and between the pixel electrode and the data lines are existing in each pixel region defined by two adjacent data lines and two adjacent gate lines. Hence, whether the light-shielding structure is the black matrix on the CF substrate or the opaque light-shielding structure on the TFT substrate, the light-shielding structure must be formed on the four sides of the pixel regions. The aperture ratio is still affected, and the quality of the LCD panel can not rise.